Platinum-rhodium stack as an oxygen barrier

ABSTRACT

The present invention relates to an electrically conductive film stack for semiconductors and methods and apparatus for providing same. A film stack comprising a first layer of a platinum-rhodium alloy deposited by metal organic chemical vapor deposition (MOCVD) in the presence of a reducer, such as hydrogen (H 2 ) gas, and a second layer of the platinum-rhodium alloy deposited in the presence of an oxidizing gas, such as ozone (O 3 ), provides an electrical conductor that is also a relatively good barrier to oxygen. The platinum-rhodium film stack can be used as an electrode or capacitor plate for a capacitor with a high-k dielectric material. The electrode formed with alternating reducing and oxidizing agents produces a rough surface texture, which enhances the memory cell capacitance.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention is generally related to semiconductorfabrication. In particular, the present invention relates to aconductive metal film stack in a semiconductor.

[0003]2. Description of the Related Art

[0004] Electrical conductors are a fundamental part of integratedcircuits. Electrical conductors can be used to connect devices and formconductive films that, in turn, can also be used as electrodes in acapacitor that is used to store charge in a memory cell. Preferably,integrated circuit capacitors feature a relatively large amount ofcapacitance in a small geometry to preserve space on the chip.

[0005] Conventional techniques for shrinking capacitor geometriesinclude processing steps that increase the area of electrodes used ascapacitor plates and include the use of high-k materials for thedielectric.

[0006] Desirable characteristics for a conductive film includerelatively good conductivity and relatively good resistance to thediffusion of oxygen. Relatively good conductivity allows a relativelylow contact string resistance to a device. Relatively good resistance tothe diffusion of oxygen provides protection to sensitive materials,particularly where the fabrication includes formation of high-kdielectric materials. Typical high-k dielectric materials, such asbarium strontium titanate (BST) (Ba_(x)Sr_(1-x)TiO₃), are rich inoxygen. A highly oxidizing environment is typically required duringformation of such high-k dielectric materials. Additionally, oxygen candiffuse from the high-k dielectric material after deposition, leavingconductive leakage paths in the dielectric as well as oxidizingneighboring materials.

[0007] In the past, various metals and alloys have been deposited aselectrical conductors. For example, platinum (Pt) is one metal that isfrequently deposited. However, films formed from platinum provide arelatively poor barrier to oxygen and allow underlying layers tooxidize. For example, if the platinum is deposited directly on silicon(Si), the diffused oxygen can result in the conversion of silicon (Si)to silicon dioxide (SiO₂), which in turn results in an increase in thecontact string resistance to the affected device. In another example,where platinum is deposited on a layer of tantalum that is used as anadhesion layer, the diffused oxygen can convert the tantalum (Ta) to anoxide of tantalum, thereby reducing the conductivity of the originaltantalum adhesion layer.

SUMMARY OF THE INVENTION

[0008] Embodiments of the present invention provide an electricallyconductive film stack for semiconductors and methods and apparatus forproviding the same. The film stack can be used either as a conductoritself or in conjunction with another conductor. Advantageously, thefilm stack can form an oxygen barrier that substantially prevents theloss of oxygen from high-k (high dielectric constant) dielectricmaterial and prevents oxidation of neighboring materials, such assilicon (Si). The film stack can be deposited on a three-dimensionalstructure, such as a wall of a high-k metal-insulator-metal (MIM)capacitor, to form an electrode for the capacitor. The electrode formedby the film stack includes graining, which enhances the surface area ofthe electrode and thereby increases the capacitance of the capacitor.

[0009] One process according to an embodiment of the present inventiondeposits an electrode for a metal-insulator-metal capacitor. Theelectrode serves as both an electrically conductive plate for thecapacitor as well as an oxygen barrier, thereby protecting neighboringmaterials. The electrode is deposited in multiple layers. A first layerof the multiple layers is a layer of platinum-rhodium (Pt-Rh) alloydeposited in a metal organic chemical vapor deposition (MOCVD) processin the presence of an oxidizer. A second layer of the platinum-rhodiumalloy is deposited on the first layer in the presence of a reducer. Athird layer of the platinum-rhodium alloy is deposited on the secondlayer, again in the presence of an oxidizer.

[0010] Another process according to an embodiment of the presentinvention deposits a metallic film stack on a substrate. A first film isdeposited with a reducer and a second film of a similar composition isdeposited on the first film with an oxidizer.

[0011] In another process according to an embodiment of the presentinvention, the process deposits a metallic film stack by alternatingbetween depositing a layer in the presence of a reducing agent, anddepositing a layer in the presence of an oxidizing agent, while usingthe same metal source gas(es) during both steps. The depositing oflayers can be repeated to build up a thickness of the film stack.

[0012] One system according to an embodiment of the present inventionprovides a MOCVD system that is adapted to alternately introduce anoxidizing reactant gas and a reducing reactant gas. A plurality ofvaporizers can prepare organometallic platinum and organometallicrhodium for introduction to the deposition chamber via a relativelyinert gas, such as argon (Ar) or helium (He).

[0013] One embodiment of the present invention includes aplatinum-rhodium alloy capacitor plate that is deposited on a substrate.The capacitor plate includes a rough texture to enhance the capacitanceof the capacitor cell. Preferably, one surface of the capacitor plateexhibits hemispherical grains with an average size of about 50 Angstroms(Å) to about 1000 Å, and more preferably of about 100 Å to about 500 Å.It will be understood by one of ordinary skill in the art that anoptimal area enhancement through the HSG Pt-Rh will vary depending onthe geometry of the capacitor. Preferably, the platinum-rhodium alloy isabout 5% to 50% rhodium by atomic ratio. More preferably, theplatinum-rhodium alloy is about 10% to 40% rhodium by atomic ratio.Additionally, the capacitor plate is preferably from about 50 Å to about1000 Å thick. More preferably, the capacitor plate is about 100 Å toabout 600 Å thick. Advantageously, the capacitor plate provides abarrier to oxygen, thereby substantially preventing the oxidation ofneighboring materials and allowing the use of high-k dielectrics.

[0014] Another embodiment according to the present invention includes ametal-insulator-metal integrated circuit capacitor. In themetal-insulator-metal capacitor, at least one of the plates orelectrodes is made from a platinum-rhodium alloy. The platinum-rhodiumalloy plate advantageously includes a grainy surface that faces thedielectric, and further advantageously provides an oxygen barrier forthe dielectric. Preferably, the dielectric is a relatively high-kmaterial with a relative permittivity of at least 5, or more preferablyat least 10. In one embodiment, the dielectric material selected is fromtantalum oxide (Ta₂O₅) and barium strontium titanate (BST)(Ba_(x)Sr_(1-x)TiO₃).

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] These and other features of the invention will now be describedwith reference to the drawings summarized below. These drawings and theassociated description are provided to illustrate preferred embodimentsof the invention, and not to limit the scope of the invention.

[0016]FIG. 1 is a flowchart, generally illustrating a process forproducing a 2-layer film stack.

[0017]FIG. 2 is a flowchart, generally illustrating a process forproducing a 3-layer film stack.

[0018]FIG. 3 is a schematic cross-sectional view of a 3-layer film stackon a substrate according to an embodiment of the present invention.

[0019]FIG. 4 is a cross-sectional view of a capacitor according to anembodiment of the present invention, where a rough film stack forms anelectrode of the capacitor.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0020] Although this invention will be described in terms of certainpreferred embodiments, other embodiments that are apparent to those ofordinary skill in the art, including embodiments which do not provideall of the benefits and features set forth herein, are also within thescope of this invention. Accordingly, the scope of the present inventionis defined only by reference to the appended claims.

[0021] Embodiments of the present invention include multiple layer filmstacks of platinum-rhodium alloy that can be used in semiconductorfabrication. The multiple layer film stacks can include from 2 layers tomany layers of platinum-rhodium alloy film. Alternating layers ofplatinum-rhodium alloy film are deposited in reducing and oxidizingenvironments, respectively. The film stack conducts electricity and canbe used, for example, as an electrode in a capacitor. In addition, thefilm stack advantageously provides an oxygen barrier, which can, forexample, substantially inhibit the oxidation of neighboring materials,particularly when employed in conjunction with high-k materials.

[0022] While referred to herein as a film “stack,” due to the differentsteps employed to deposit the material, the skilled artisan willappreciate that the layers within the stack are all of a similarcomposition. In the illustrated embodiment, this means that the entirestack comprises a platinum-rhodium (Pt-Rh) alloy, although individuallayers within the stack can exhibit slightly different ratios ofcomponent metals.

[0023]FIG. 1 illustrates a process 100 according to one embodiment ofthe present invention for producing a 2-layer film stack. In State 110,a substrate is introduced to a deposition chamber of a deposition systemand the system prepares for deposition. The substrate can include asingle wafer for a single wafer deposition system, or can includemultiple wafers in a batch wafer deposition system. One embodiment ofthe process 100 is a metal organic chemical vapor deposition (MOCVD)process. Other terms used in the literature to describe MOCVD includeorgano-metal vapor phase epitaxy (OMVPE) and metal organic vapor phaseepitaxy (MOVPE).

[0024] The substrate can conform to a variety of physical geometries,including substantially planar geometries or complex three-dimensionalstructures, such as those that are used to fabricate capacitors (see,e.g., FIG. 4 and accompanying text).

[0025] State 110 further includes aspects of a MOCVD process that arewell known to those of ordinary skill in the art. For example, thetemperature of the deposition chamber, or at least the temperature ofthe substrate, is preferably maintained within a range of approximately150 degrees Celsius (C) to 550 degrees C. More preferably, thetemperature is maintained within a range of approximately 200 degrees Cto 500 degrees C. One embodiment maintains a temperature of about 450degrees C. Typical sources for heat include radiant heat from tungstenhalogen lamps or ultraviolet sources, inductive heating, resistanceheating, etc. Typical MOCVD chamber pressures, such as between 0.1 Torrand 100 Torr, can be used. The process advances from State 110 to State120.

[0026] In State 120, the system deposits a first layer of platinum andrhodium on the substrate with a reducer. It will be understood by one ofordinary skill in the art that the first layer can be deposited directlyon a substrate, such as silicon, or can be deposited on another layerthat is already present on the substrate, such as an adhesion layer oftitanium nitride (TiN) or tantalum (Ta).

[0027] The sources for platinum and rhodium are introduced to thedeposition chamber in a gas vapor phase. The gas vapor phase of platinumcan be obtained by heating an organometallic platinum precursor, such asPt(acac)₂, in a vaporizer and using an inert gas, such as argon (Ar) ornitrogen (N₂), to carry the organometallic platinum precursor to thedeposition chamber. Similarly, the gas vapor phase of rhodium can beintroduced to the deposition chamber by heating an organometallicrhodium precursor, such as Rh(CO)₂(acac), in a vaporizer and carryingthe organometallic rhodium precursor to the deposition chamber with aninert gas. It will be understood by one of ordinary skill in the artthat the flow rate of the carrier gases will depend on the size of thedeposition chamber. Examples of flow ranges include about 10 standardcubic centimeters per minute (SCCM) to about 1000 SCCM.

[0028] The relative gas flow rates between the carrier gas with theplatinum precursor and the carrier gas with the rhodium precursorcontrol the relative ratio of platinum to rhodium in the deposited film.Preferably, the gas flow rates are maintained such that the depositedplatinum-rhodium alloy film comprises from about 5% to about 50% rhodiumas measured by atomic ratio. More preferably, the gas flow rates areadjusted so that the deposited platinum-rhodium alloy comprises fromabout 10% to about 40% rhodium. In one embodiment, the gas flow ratesare adjusted so that the platinum-rhodium alloy is about 70/30 platinumto rhodium. One embodiment of the system provides for the adjustment ofthe relative gas flows of platinum and rhodium carrier gases, by gasflow valves and the like, so that the ratio of platinum to rhodium canbe configured to conform to design choice. One embodiment of the systemincludes mass flow controllers under software control, where thesoftware is programmed to maintain the flow of the source gases forplatinum and rhodium, and to select among reactant gases, includingoxidizing reactant gases and reducing reactant gases.

[0029] In addition, in State 120, the platinum-rhodium alloy isdeposited in the presence of a reducing gas or reducer. Examples ofsources for the reducing gas include hydrogen (H₂) and ammonia (NH₃).The reducing gases can be used alone, or in combination. Depositing inthe presence of a reducing atmosphere results in a relatively slowdeposition rate. While the deposition rate with an oxidizer is generallyhigher than the deposition rate with a reducer, the inventors have foundpronounced advantages to processes that include a reducing agent in atleast one phase.

[0030] Preferably, the deposition of a platinum-rhodium alloy film inthe presence of a reducing gas continues until the thickness of the filmis from about 20 Angstroms (Å) to about 500 Å. The process advances fromState 120 to State 130.

[0031] In State 130, the process continues to deposit theplatinum-rhodium alloy, but in the presence of an oxidizing gas oroxidizer. The source for the reducing gas is substantially cut-off andinstead, an oxidizing gas is introduced to the deposition chamber.Examples of source gases that can be used as the oxidizing gas includeoxygen (O₂), ozone (O₃), nitrous oxide (N₂O), hydrogen peroxide (H₂O₂),steam (H₂O), and nitric oxide (NO). The oxidizing gases can be usedalone, or in combination. Preferably, deposition of a platinum-rhodiumalloy film in the presence of an oxidizing gas continues until thethickness of the film is from about 20 Angstroms (Å) to about 500 Å.

[0032] Advantageously, the deposition of the platinum-rhodium alloyfilms described above in States 120 and 130 can be accomplished in onerecipe, i.e., without removing the substrate from the depositionchamber, by switching reducer flow to oxidizer flow and maintaining theflow of the metal source gases. Preferably, the total thickness of a2-layer film stack deposited by the process 100 is from about 50 Å toabout 2000 Å thick. More preferably, the film stack is from about 100 Åto about 1000 Å thick. It will be understood by one of ordinary skill inthe art that the film stack referenced above can form a portion of alarger structure. For example, the film stack may be deposited on top ofa silicon (Si) substrate directly, or may be deposited on a layer orlayers that have already been deposited on the substrate, such as, forexample, a layer of titanium nitride (TiN) or a layer of platinum (Pt).Further, additional layers can be deposited on top of the film stack.For example, a layer of ruthenium oxide (RuO₂) can be deposited on topof the film stack.

[0033] Advantageously, the 2-layer film stack of platinum-rhodium alloyis both electrically conductive and a barrier to oxygen. Theplatinum-rhodium alloy typically exhibits a resistivity of 30microohm-centimeters (μΩ-cm). The electrical conductivity allows thefilm stack to be used to connect to devices, such as transistors. Inaddition, electrical conductivity allows a film stack to form at least aportion of an electrode for a capacitor. The capacitor can store charge,and hence, can be used to form part of a memory device such as a dynamicread only memory (DRAM) chip.

[0034] Further, the combination of deposition with a reducer anddeposition with an oxidizer results in a 2-layer film stack that forms arelatively good barrier to oxygen. The barrier to oxygen cansubstantially prevent the diffusion of oxygen during formation andannealing of a high-dielectric constant material, such as bariumstrontium titanate (BST) (Ba_(x)Sr_(1-x)TiO₃). Oxidation of neighboringmaterials, such as underlying silicon (Si), is undesirable because thesilicon (Si) converts to silicon dioxide (SiO₂), which increases thecontact string resistance of the associated component or device.Reduction of BST is undesirable because the BST dielectric converts toconductive metallics, which discharge the charge stored in the capacitorthrough leakage. Advantageously, a 2-layer film stack produced inaccordance with the process 100 described above can substantiallyprevent the unintended diffusion of oxygen and preserves neighboringmaterials.

[0035] In addition, the 2-layer film stack deposited by alternating thereducer and the oxidizer results in a rough surface texture. The grainsize achieved by alternating the reducer and the oxidizer is from about100 Å to about 500 Å.

[0036] A rough surface has a relatively larger surface area than asmooth surface. In a capacitor, a larger surface area is desirablebecause the capacitance of a capacitor is approximately proportional tothe effective surface area of the electrodes. An electrode according toan embodiment of the present invention exhibits a 70 to 100% increase insurface area compared with a substantially planar surface. By providinga method to increase the relative capacity of a capacitor, a geometry ofthe capacitor can be decreased for a given amount of capacitance andmore capacitors can be fabricated in a given area of substrate.Advantageously, relatively larger and more reliable memory devices canbe fabricated and/or the same memory size devices can be fabricated on asmaller portion of substrate. Examples of dielectric materials that canbe used to fabricate a capacitor include tantalum oxide (Ta₂O₅) andbarium strontium titanate (BST) (Ba_(x)Sr_(1-x)TiO₃). Beneficially, anelectrode according to an embodiment of the present invention furtherprovides an oxygen barrier so that a high-k dielectric, such as Ta₂O₅ orBST can be used, thereby combining the benefits of a high-k dielectricand a relatively large surface area.

[0037] By contrast, typical methods to increase the relative surfacearea of a deposited film involve silicon electrodes, which are easilyoxidized. For example, in a conventional system, a layer of polysiliconcan be made hemispherical grain (HSG), over which layers ofmetallization are deposited.

[0038] Embodiments of the present invention obviate the need tospecially prepare the surface by providing a method of producing agrainy film stack on a smooth surface. In addition, the surfaces towhich a film stack can be deposited include both substantially flatsurfaces as well as 3-dimensional surfaces, as can be found in a trenchof etched substrate material.

[0039] The process 100 can be repeated multiple times so that a filmstack includes multiple layers of platinum-rhodium alloy deposited withalternating reducing agents and oxidizing agents. Preferably, theresulting film stack, with multiple layers deposited by repeating theprocess 100, is from about 50 Å to about 2000 Å thick. More preferably,the film stack is from about 100 Å to about 1000 Å thick. Preferably, alayer in the film stack is from about 20 Å to about 500 Å thick.

[0040]FIG. 2 illustrates a process 200 according to an embodiment of thepresent invention of alternating multiple films deposited with reducingagents and oxidizing agents. In the process 200 shown in FIG. 2, a3-layer film stack is deposited on a substrate. In sequence, the process200 comprises the States 110, 210, 120, and 130.

[0041] In State 110, a substrate is introduced to a deposition chamberof a deposition system and the system prepares for deposition. Furtherdetails of State 110 are described above in connection with FIG. 1. Theprocess advances from State 110 to State 210.

[0042] In State 210, the process 200 deposits a layer ofplatinum-rhodium alloy in the presence of an oxidizing gas. As describedabove in connection with State 130 of the process 100 illustrated inFIG. 1, the oxidizing gas can include gases such as oxygen (O₂), ozone(O₃), nitrous oxide (N₂O), hydrogen peroxide (H₂O₂), steam (H₂O), andnitric oxide (NO). Preferably, the deposition of a platinum-rhodiumalloy film in State 210 continues until the thickness of the film isfrom about 20 Å to about 500 Å. The process advances from State 210 toState 120.

[0043] In State 120, the process 200 deposits a layer of platinum andrhodium with a reducer. The layer deposited in State 120 is deposited ontop of the layer of platinum-rhodium alloy that was deposited with theoxidizer in State 210. Further details of State 120 are described abovein connection with FIG. 1. Preferably, the deposition of aplatinum-rhodium alloy film in State 120 continues until the thicknessof the film is from about 20 Å to about 500 Å. The process advances fromState 120 to State 130.

[0044] In State 130, the process deposits the platinum-rhodium alloywith an oxidizer on top of the layer of platinum-rhodium alloy that wasdeposited with the reducer in State 120. Further details of State 130are described above in connection with FIG. 1. Again, the deposition ofa platinum-rhodium alloy film that is deposited in the presence of anoxidizing gas in State 130 preferably continues until the thickness ofthe film is from about 20 Angstroms (Å) to about 500 Å.

[0045] Advantageously, the deposition of the multiple layerplatinum-rhodium alloy film stack produced by the process 200 describedin connection with FIG. 2 can be accomplished in one recipe, i.e.,without removing the substrate from the deposition chamber, by switchingreducer flow to oxidizer flow and vice-versa while maintaining the flowof other source gases. Preferably, the total thickness of a 3-layer filmstack deposited by the process 200 is again from about 50 Å to about2000 Å thick. More preferably, the film stack is from about 100 Å toabout 1000 Å thick. The 3-layer film stack produced by the process 200again possesses the benefits of providing electrical conductivity and ofproviding a barrier to oxygen.

[0046]FIG. 3 illustrates a cross-sectional view of a 3-layer film stack300 deposited on a substrate 310 according to an embodiment of thepresent invention. The film stack 300 can be deposited on an optionaladhesion layer 320, which can be fabricated from, for example, a layerof titanium nitride (TiN) or tantalum (Ta). The adhesion layer 320 isdeposited on the substrate 310. Where the adhesion layer 320 is notused, the film stack 300 can be deposited on the substrate 310 or on acontact plug. The film stack can also be deposited on a dielectric andused as a top electrode.

[0047] A first layer 330 of the film stack is deposited on the adhesionlayer 320. The first layer 330 can be deposited in accordance with State210 of the process 200, i.e., deposited with an oxidizer. Preferably,the first layer 330 is from about 20 Å to about 500 Å thick.

[0048] A second layer 340 of the film stack is deposited on the firstlayer 330. The second layer 340 can be deposited in accordance withState 120 of the process 200, i.e., deposited with a reducer.Preferably, the second layer 340 is from about 20 Å to about 500 Åthick.

[0049] A third layer 350 of the film stack is deposited on the secondlayer 340. The third layer 350 can be deposited in accordance with State130 of the process 200, i.e., deposited with an oxidizer. Preferably,the third layer 350 is from about 20 Å to about 500 Å thick.

[0050] In one embodiment, the total film stack thickness, i.e., the sumof the thickness of the first, the second, and the third layers, 330,340, 350 is from about 50 Å to about 2000 Å thick. Preferably, the totalfilm stack thickness is from about 100 Å to about 1000 Å thick.

[0051] In one embodiment, the deposited films 330, 340, 350 of the filmstack comprise an alloy of platinum and rhodium. Preferably, theplatinum-rhodium alloy ranges from about 5% to about 50% rhodium byatomic ratio. More preferably, the platinum-rhodium alloy ranges fromabout 10% to about 40% rhodium as measured by atomic ratio. Oneembodiment of the film stack 300 uses the same ratio of platinum torhodium in the films. Of course, the ratio of platinum to rhodium can beeasily varied between deposition of the layers if so desired, by, forexample, manipulating the carrier gas flow rates.

[0052] It will be understood by one of ordinary skill in the art thatother embodiments of the film stack include 2-layer film stacks andmultiple layer film stacks. The 3-layer film stack 300 shown in FIG. 3merely represents one possible configuration of a film stack accordingto an embodiment of the present invention.

[0053]FIG. 4 illustrates one embodiment of the present invention of ametal-insulator-metal capacitor 400, where a film stack forms anelectrode of the capacitor 400. The capacitor 400 can serve to storecharge for a cell of a memory device, such as a cell of a DRAM. It willbe understood by one of ordinary skill in the art that manyconfigurations for the capacitor are possible. For example, oneembodiment according to the present invention includes a stack capacitorformed above transistors, where the stack capacitor is formed bycreating a hole or well in a thick insulator, and lining the hole withelectrode layers and dielectric layers.

[0054] In the illustrated embodiment, the capacitor 400 shown in FIG. 4is formed within a trench that is etched into the substrate 410. A firstplate or first electrode 420 is formed on the substrate 420. In oneembodiment of the capacitor 400, the first electrode 420 is a film stackdeposited in accordance with an embodiment of the present invention,such as the film stack 300 shown in FIG. 3.

[0055] A dielectric layer 430 is formed on top of the first electrode420. Examples of materials for the dielectric layer include bariumstrontium titanate (BST) (Ba_(x)Sr_(1-x)TiO₃), tantalum oxide (Ta₂O₅),silicon nitride (Si₃N₄), silicon dioxide (SiO₂), zirconium oxide (ZrO₂),hafnium oxide (HfO₂), niobium oxide (Nb₂O₅) and others. Preferably, thedielectric material used in a capacitor according to an embodiment ofthe present invention has a k value (relative permittivity) greater thanabout 5, and more preferably, has a k value greater than about 10.

[0056] A second electrode 440 is formed on top of the dielectric layer430. In one embodiment, both the first and the second electrodes 420,440 conform to film stacks produced in accordance with an embodiment ofthe present invention. In another embodiment, only one of the first orthe second electrodes 420, 440 conform to film stacks produced inaccordance with an embodiment of the present invention.

[0057] Various embodiments of the present invention have been describedabove. Although this invention has been described with reference tothese specific embodiments, the descriptions are intended to beillustrative of the invention and are not intended to be limiting.Various modifications and applications may occur to those skilled in theart without departing from the true spirit and scope of the invention asdefined in the appended claims.

We claim:
 1. A metal organic chemical vapor deposition (MOCVD) process that deposits an electrode for a metal-insulator-metal capacitor in an integrated circuit substrate, the process comprising: flowing a first oxidizer while depositing a first layer of platinum-rhodium alloy on the substrate; flowing a reducer while depositing a second layer of platinum-rhodium alloy on the first layer; and flowing a second oxidizer while depositing a third layer of platinum-rhodium alloy on the second layer.
 2. The method as defined in claim 1, wherein the first and the second oxidizer both comprise nitrous oxide (N₂O) and the reducer comprises hydrogen (H₂).
 3. The method as defined in claim 1, wherein depositing the electrode is performed in one recipe.
 4. A process of depositing a metallic film stack on a substrate in accordance with a metal organic chemical vapor deposition (MOCVD) process, the process comprising: depositing a first film of a metal composition in the presence of a reducer; and depositing a second film of the metal composition in the presence of an oxidizer, the second film directly contacting the first film.
 5. The process as defined in claim 4, wherein the metal composition comprises an alloy of platinum and rhodium.
 6. The process as defined in claim 4, wherein the reducer is selected from hydrogen (H₂) and ammonia (NH₃).
 7. The process as defined in claim 4, wherein the oxidizer is selected from oxygen (O₂), ozone (O₃), nitrous oxide (N₂O), hydrogen peroxide (H₂O₂), steam (H₂O), and nitric oxide (NO).
 8. The process as defined in claim 4, wherein depositing the film stack is conducted in one recipe.
 9. The process as defined in claim 4, further comprising depositing a third film of the metal composition in the presence of the oxidizer before depositing the first film.
 10. The process as defined in claim 4, wherein a thickness of the film stack is from about 50 Angstroms (Å) to about 2000 Å.
 11. The process as defined in claim 4, wherein a thickness of the film stack is from about 100 Å to about 1000 Å.
 12. The process as defined in claim 4, wherein a thickness of the first film is about 20 Å to about 500 Å.
 13. The process as defined in claim 4, wherein a thickness of the second film is about 20 Å to about 500 Å.
 14. A method of depositing a metallic film stack on a substrate in accordance with a metal organic chemical vapor deposition (MOCVD) process, the method comprising: depositing a plurality of layers of a metallic composition on the substrate by alternating between: depositing a layer with a metal source gas using a reducing agent; and depositing a layer with the same metal source gas using an oxidizing agent.
 15. The method as defined in claim 14, wherein depositing the plurality of layers forms a total thickness of the film stack between about 100 Å and about 1000 Å.
 16. The method as defined in claim 14, wherein depositing using the reducing agent forms a layer thickness between about 20 Å and about 500 Å thick.
 17. The method as defined in claim 14, wherein depositing using the oxidizing agent forms a layer thickness between about 20 Å and about 500 Å thick.
 18. A system adapted to deposit a layered film on a substrate substantially in accordance with a metal organic chemical vapor deposition (MOCVD) process, the system comprising: a chamber adapted to house the substrate and to maintain a controlled environment that includes maintaining a substrate temperature to within 200 degrees to 550 degrees Celsius during deposition, the chamber further adapted to maintain a low pressure in the chamber; an inlet system adapted to introduce reactant gases and organometallic precursors in gas vapor phase to the chamber; and an alternating system adapted to maintain the flow of the organometallic precursors in gas vapor phase while alternating between a reducing reactant gas and an oxidizing reactant gas.
 19. The system as defined in claim 18, wherein the organometallic precursors are introduced by a plurality of vaporizers coupled to the chamber, wherein one vaporizer is adapted to heat and to flow a platinum source and another vaporizer is adapted to heat and to flow a rhodium source.
 20. A rough capacitor plate in an integrated circuit, comprising platinum-rhodium alloy electrically connected to an active area of an underlying substrate, where a surface of the capacitor plate includes a rough surface texture.
 21. The capacitor plate as defined in claim 20, wherein the surface has hemispherical grains with an average size about between about 50 Å and about 1000 Å.
 22. The capacitor plate as defined in claim 20, wherein the surface has hemispherical grains with an average size between about 100 Å and about 500 Å.
 23. The capacitor plate as defined in claim 20, wherein the capacitor plate has a thickness between about 50 Å and about 2000 Å.
 24. The capacitor plate as defined in claim 20, wherein the capacitor plate has a thickness between about 100 Å and about 1000 Å thick.
 25. The capacitor plate as defined in claim 20, wherein about 5% to 50% of the platinum-rhodium alloy is rhodium.
 26. The capacitor plate as defined in claim 20, wherein about 10% to 40% of the platinum-rhodium alloy is rhodium.
 27. A metal-insulator-metal integrated circuit capacitor, comprising: a first plate of platinum-rhodium alloy electrically connected to an active area of an underlying substrate, wherein a surface of the first plate of platinum-rhodium alloy facing the dielectric has hemispherical grains with an average size between about 50 Å and about 1000 Å; a second plate; and a dielectric disposed between the first plate and the second plate, where the dielectric has a relative permittivity of at least
 5. 28. The capacitor as defined in claim 27, wherein the dielectric has a relative permittivity of at least
 10. 29. The capacitor as defined in claim 27, wherein dielectric is selected from tantalum oxide (Ta₂O₅) and barium strontium titanate (BST) (Ba_(x)Sr_(1-x)TiO₃).
 30. The capacitor as defined in claim 27, wherein a surface of the first plate of platinum-rhodium alloy facing the dielectric has hemispherical grains with an average size between about 100 Å and about 500 Å. 